im currently inclined to shell helix diesel in my next oil change,my ride is ford everest and may nagsabi taga ford na if you use shell oils extend nila engine warranty to 3 years. Why is that so? are shell diesel oils significantly better than other brands? Im currently using fully synthetic mobil1 0w-40 pero napansin ko wala naman improvements on fuel consumption and acceleration compared to mineral multigrade oils, (parang mas lumakas pa nga laklak ng diesel). So im thinking of switching back to mineral oils and im considering the shell helix diesel. Ano ba viscosity and ratings nito?The manual recommends 5w-30 or 10w-30.ang shell rimula ba hindi multigrade? thanks in advance